CA2682094A1 - Electrode active material and lithium secondary battery - Google Patents
Electrode active material and lithium secondary battery Download PDFInfo
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- CA2682094A1 CA2682094A1 CA002682094A CA2682094A CA2682094A1 CA 2682094 A1 CA2682094 A1 CA 2682094A1 CA 002682094 A CA002682094 A CA 002682094A CA 2682094 A CA2682094 A CA 2682094A CA 2682094 A1 CA2682094 A1 CA 2682094A1
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- Prior art keywords
- electrode active
- active material
- valence
- electrolyte solution
- amorphous
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- 239000007772 electrode material Substances 0.000 title claims abstract description 88
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims description 22
- 229910052744 lithium Inorganic materials 0.000 title claims description 22
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 32
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 32
- 230000014509 gene expression Effects 0.000 claims abstract description 25
- 239000003792 electrolyte Substances 0.000 claims abstract description 24
- 239000011521 glass Substances 0.000 claims abstract description 16
- 239000002994 raw material Substances 0.000 claims description 33
- 239000000203 mixture Substances 0.000 claims description 19
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical group [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 7
- 229910052796 boron Inorganic materials 0.000 claims description 7
- 239000007774 positive electrode material Substances 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000007773 negative electrode material Substances 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 54
- 230000003647 oxidation Effects 0.000 description 24
- 238000007254 oxidation reaction Methods 0.000 description 24
- 238000012360 testing method Methods 0.000 description 14
- 238000007599 discharging Methods 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- -1 LiPF6 Chemical class 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 239000006258 conductive agent Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 229910052723 transition metal Inorganic materials 0.000 description 4
- 150000003624 transition metals Chemical class 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 239000004745 nonwoven fabric Substances 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 2
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 2
- 229910001290 LiPF6 Inorganic materials 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 239000005300 metallic glass Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- LZDKZFUFMNSQCJ-UHFFFAOYSA-N 1,2-diethoxyethane Chemical compound CCOCCOCC LZDKZFUFMNSQCJ-UHFFFAOYSA-N 0.000 description 1
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 description 1
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910016523 CuKa Inorganic materials 0.000 description 1
- 229910000733 Li alloy Inorganic materials 0.000 description 1
- 229910011084 Li2Fe Inorganic materials 0.000 description 1
- 229910000552 LiCF3SO3 Inorganic materials 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000000010 aprotic solvent Substances 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 150000004696 coordination complex Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- CYCWUPSOUXBFCK-UHFFFAOYSA-N diethyl carbonate;dimethyl carbonate;ethyl methyl carbonate Chemical compound COC(=O)OC.CCOC(=O)OC.CCOC(=O)OCC CYCWUPSOUXBFCK-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 150000004698 iron complex Chemical class 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 239000001989 lithium alloy Substances 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052976 metal sulfide Inorganic materials 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- FVSKHRXBFJPNKK-UHFFFAOYSA-N propionitrile Chemical compound CCC#N FVSKHRXBFJPNKK-UHFFFAOYSA-N 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 description 1
- 150000003457 sulfones Chemical class 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/12—Silica-free oxide glass compositions
- C03C3/14—Silica-free oxide glass compositions containing boron
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C4/00—Compositions for glass with special properties
- C03C4/18—Compositions for glass with special properties for ion-sensitive glass
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Electrode active material that is used together with an electrolyte solution having an electrolyte decomposition potential Ve is represented by the general expression LixFeMyO2 and is amorphous. In the expression, x and y are values which independently satisfy 1 < x <= 2.5 and O < y <= 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, and M represents one or two or more types of glass former element. The average electronegativity of M is less than (Ve + 6.74 / 5.41.
Description
ELECTRODE ACTIVE MATERIALAND LITHIUM SECONDARY BATTERY
BACKGROUND OF THE INVENTION
1. Field of the Invention [0001] The invention relates to amorphous electrode active material which has superior charging and discharging characteristics, and a lithium secondary battery which uses that amorphous electrode active material.
". Description of the Related Art [0002] As personal computers, video cameras, mobile phones and other such devices become smaller, lithium secondary batteries have come to be widely used as power sources in the fields of communication and information-related devices due to their high energy density. Also, in the automotive field as well, there is a push for the rapid development of electric vehicles due to environmental and resources issues, and lithium secondary batteries are being considered for use as power sources to power these electric vehicles.
BACKGROUND OF THE INVENTION
1. Field of the Invention [0001] The invention relates to amorphous electrode active material which has superior charging and discharging characteristics, and a lithium secondary battery which uses that amorphous electrode active material.
". Description of the Related Art [0002] As personal computers, video cameras, mobile phones and other such devices become smaller, lithium secondary batteries have come to be widely used as power sources in the fields of communication and information-related devices due to their high energy density. Also, in the automotive field as well, there is a push for the rapid development of electric vehicles due to environmental and resources issues, and lithium secondary batteries are being considered for use as power sources to power these electric vehicles.
[0003] Currently amorphous electrode active material is known to be used as the electrode active material in lithium secondary batteries. For example, Japanese Patent Application Publication No. 2005-135866 (JP-A-2005-135866) describes electrode active material that is mainly an amorphous metal complex represented by the general expression M2_1;B2XO3. Also, Japanese Patent Application Publication No. 8-(JP-A-8-78002) describes positive electrode active material that is made up of an oxide of a transition metal from the 7A family or an oxide of a transition metal from the 8A family or both, in which a portion of that transition metal oxide has an amorphous structure.
Further, Japanese Paten,t Application Publication No. 10-74515 (JP-A-10r74515) describes positive electrode active material in which a transition metal from the 7A
family or a transition metal from the 8A family or both is Me, and in which a portion or all that has a LiMeO2 structure is made up of an amorphous metal oxide.
Further, Japanese Paten,t Application Publication No. 10-74515 (JP-A-10r74515) describes positive electrode active material in which a transition metal from the 7A
family or a transition metal from the 8A family or both is Me, and in which a portion or all that has a LiMeO2 structure is made up of an amorphous metal oxide.
[0004] Amorphous electrode active material is advantageous in that the composition can be set freely compared with crystalline electrode active material.
Moreover, although amorphous electrode active material shows promise as a high capacity electrode active material, its actual capacity is currently still low so there is a demand for high capacity amorphous electrode active material. Incidentally, Japanese Patent Application Publication No. 10-134813 (JP-A-10-134813) and Japanese Patent Application Publication No. 9-22695 (JP-A-9-22695) both describe electrode active material and the like which, although not amorphous, does consist mainly of an iron complex FeBO3 or the like.
SUMMARY OF THE INVENTION
Moreover, although amorphous electrode active material shows promise as a high capacity electrode active material, its actual capacity is currently still low so there is a demand for high capacity amorphous electrode active material. Incidentally, Japanese Patent Application Publication No. 10-134813 (JP-A-10-134813) and Japanese Patent Application Publication No. 9-22695 (JP-A-9-22695) both describe electrode active material and the like which, although not amorphous, does consist mainly of an iron complex FeBO3 or the like.
SUMMARY OF THE INVENTION
[0005] This invention provides amorphous electrode active material with superior charging and discharging characteristics.
[0006] The inventors have found a correlative relationship between the oxidation potential of Fe and the average electronegativity of M in amorphous electrode active material represented by the general expression LixFeM},Oz (where M is a one or two or more types of glass former element). More specifically, the inventors have found that the oxidation potential of Fe drops when the average electronegativity of M
decreases, and that not only divalent-trivalent redox (i.e., oxidation-reduction) of Fe, but also trivalent-quadrivalent redox of Fe can be put to practical use. Normally, the oxidation potential from trivalent Fe to quadrivalent Fe is higher than the decomposition potential of the electrolyte solution (hereinafter also referred to as "electrolyte decomposition potential") so if the potential is increased, the electrolyte solution starts to decompose first, thus preventing trivalent-quadrivalent redox from being put to practical use. However, the inventors have found that by controlling the aver4ge electronegativity of M, the oxidation potential from trivalent Fe to quadrivalent Fe can be lowered, and as a result, trivalent-quadrivalent redox of Fe can be actively used.
decreases, and that not only divalent-trivalent redox (i.e., oxidation-reduction) of Fe, but also trivalent-quadrivalent redox of Fe can be put to practical use. Normally, the oxidation potential from trivalent Fe to quadrivalent Fe is higher than the decomposition potential of the electrolyte solution (hereinafter also referred to as "electrolyte decomposition potential") so if the potential is increased, the electrolyte solution starts to decompose first, thus preventing trivalent-quadrivalent redox from being put to practical use. However, the inventors have found that by controlling the aver4ge electronegativity of M, the oxidation potential from trivalent Fe to quadrivalent Fe can be lowered, and as a result, trivalent-quadrivalent redox of Fe can be actively used.
[0007] A first aspect of the invention relates to an electrode active material provided with an electrolyte solution having an electrolyte decomposition potential Ve.
This electrode active material is amorphous and is represented by a general expression LiXFeMyO., where x and y are values which independently satisfy 1< x s 2.5 and 0 < y s 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve + 6.74) / 5.41.
This electrode active material is amorphous and is represented by a general expression LiXFeMyO., where x and y are values which independently satisfy 1< x s 2.5 and 0 < y s 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve + 6.74) / 5.41.
[0008] According to this first aspect, the oxidation potential from trivalent Fe to quadrivalent Fe can be reduced so that it is lower than the electrolyte decomposition potential by setting the average electronegativity of M taking the electrolyte decomposition potential Ve into account. As a result, trivalent-quadrivalent redox can be used, thus enabling high capacity electrode active material to be obtained.
[0009] Also, the average electronegativity of M may be equal to or less than 2.07. This enables a more practical electrode active material to be obtained.
[0010] Further, the M may be B (boron). Accordingly, the electronegativity can be kept within an appropriate range such that high capacity electrode active material can be obtained.
[0011] A second aspect of the invention relates to a manufacturing method of electrode active material provided with an electrolyte solution having an electrolyte decomposition potential Ve. This manufacturing method includes melt mixing raw material composition that includes raw materials that constitute a general expression LiXFeMyOZ, and rapidly solidifying from a molten state the raw material composition that was melt mixed. In the expression, x and y are values which independently satisfy 1< x S 2.5 and 0 < y s 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve + 6.74) / 5.41.
[0012] According to thek second aspect, the oxidation potential from trivalent Fe to quadrivalent Fe can be reduced so that it is lower than the electrolyte decomposition potential by setting the average electronegativity of M taking the electrolyte decomposition potential Ve into account. As a result, trivalent-quadrivalent redox can be used, thus enabling high capacity electrode active material to be obtained.
[0013] A third aspect of the invention relates to a lithium secondary battery that includes a positive electrode layer that includes the electrode active material described above as positive electrode active material, a negative electrode layer that includes negative electrode active material, a separator arranged between the positive electrode layer and the negative electrode layer, and an electrolyte solution having an electrolyte decomposition potential Ve which is impregnated into at least the separator.
[0014] According to this third aspect, a high capacity lithium secondary battery can be obtained by combining the foregoing electrode active material with the foregoing electrolyte solution.
[0015] According to the invention, amorphous electrode active material with superior charging and discharging characteristics can be obtained such, that the capacity of a lithium secondary battery and the like can be increased.
BRIEF DESCRIPTION OF THE DRAWINGS
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing and further features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent lil:e elements and wherein:
FIGS. 1A and 1B are graphs showing the relationship between the oxidation potential of Fe and the average electronegativity of M in amorphous electrode active material represented by the general expression LiXFeMyOzi FIG. 2 is a graph showing the charging and discharging characteristics of test cells according to an example; and FIG. 3 is a graph showing the rejationship between the oxidation potential of Fe and the average electronegativity of M in amorphous electrode active material according to the example.
DETAILED DESCRIPTION OF THE EMBODIMENTS
FIGS. 1A and 1B are graphs showing the relationship between the oxidation potential of Fe and the average electronegativity of M in amorphous electrode active material represented by the general expression LiXFeMyOzi FIG. 2 is a graph showing the charging and discharging characteristics of test cells according to an example; and FIG. 3 is a graph showing the rejationship between the oxidation potential of Fe and the average electronegativity of M in amorphous electrode active material according to the example.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0017] Hereinafter, electrode active material and a lithium secondary battery according to the invention will be described in detail.
[0018] First the electrode active material according to a first example 5 embodiment of the invention will be described. The electrode active material according to this example embodiment of the invention is electrode active material which is used together with electrolyte solution having an electrolyte decomposition potential Ve. The electrode active material is amorphous and can be represented by the general expression LiaFeMyO,, where x and y are values which independently satisfy 1< x s 2.5 and 0 < y<_ 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) /-2 to satisfy stoichiometry. Also, M represents one or two or more types of glass former element, and the average electronegativity of M is less than (Ve + 6.74) / 5.41.
[0019] According to the example embodiment of the invention, the oxidation potential from trivalent to quadrivalent Fe can be reduced so that it is less than the electrolyte decomposition potential by setting the average electronegativity of M taking the electrolyte decomposition potential Ve into account. As a result, trivalent-quadrivalent redox can be used which enables high capacity electrode active material to be obtained. Furthermore, the electrode active material according to the example embodiment of the invention is amorphous which is advantageous in that it enables the composition of the electrode active material to be set freely.
Incidentally, the electrode active material according to the example embodiment of the invention is normally used as positive electrode active material. Also, hereinafter, the electrode active material according to the example embodiment of the invention may be referred to as amorphous electrode active material represented by the general expression Li,FeMyOZ.
Incidentally, the electrode active material according to the example embodiment of the invention is normally used as positive electrode active material. Also, hereinafter, the electrode active material according to the example embodiment of the invention may be referred to as amorphous electrode active material represented by the general expression Li,FeMyOZ.
[0020] FIGS. 1A and 1B are graphs showing the relationship between the oxidation potential of Fe and the average electronegativity of M in amorphous electrode active material represented by the general expression LiXFeMyOZ. As shown in FIG. 1A, with amorphous electrode active material represented by the general expression Li,,FeMyOZ, when the x-axis represents the average electronegativity of M and the y-axis represents the potential (V vs Li-metal), the relationship Y = 5.41X - 6.74 is satisfied for the oxidation potential from trivalent Fe to quadrivalent Fe, and the relationship Y
5.41X - 8.54 is satisfied for the oxidation potential from divalent to trivalent Fe.
5.41X - 8.54 is satisfied for the oxidation potential from divalent to trivalent Fe.
[0021] In the related art, the oxidation potential from trivalent to quadrivalent Fe is higher than the decomposition potential of the electrolyte solution used so the electrolyte solution is first to decompose when the potential is increased. As a result, trivalent-quadrivalent redox was unable to be used. However, in this example embodiment of the invention, as shown in FIG. 113, when the electrolyte decomposition potential is Ve (V vs Li-metal), the average electronegativity of M is set to correspond to that Ve. More specifically, the average electronegativity of M is made less than (Ve +
6.74) / 5.41. As a result, the oxidation potential from trivalent to quadrivalent Fe becomes less than the decomposition potential of the electrolyte solution used so trivalent-quadrivalent redox can be used, thus enabling high capacity electrode active material to be obtained. In this manner, the average electronegativity of M in this example embodiment of the invention is defined as being less than (Ve + 6.74) / 5.41.
Hereinafter, the electrode active material according to the example embodiment of the invention will be described divided into the following: i) the structure of the electrode active material, ii) the electrolyte solution used with the electrode active material, and iii) the manufacturing method of the electrode active material.
6.74) / 5.41. As a result, the oxidation potential from trivalent to quadrivalent Fe becomes less than the decomposition potential of the electrolyte solution used so trivalent-quadrivalent redox can be used, thus enabling high capacity electrode active material to be obtained. In this manner, the average electronegativity of M in this example embodiment of the invention is defined as being less than (Ve + 6.74) / 5.41.
Hereinafter, the electrode active material according to the example embodiment of the invention will be described divided into the following: i) the structure of the electrode active material, ii) the electrolyte solution used with the electrode active material, and iii) the manufacturing method of the electrode active material.
[0022] The electrode active material according to the example embodiment of the invention is amorphous and is represented by the general expression LiaFeMyOz, where x and y are values which independently satisfy 1 < x s'?.5 and 0 < y s 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M represents one or two or more types of glass former element, and the average electronegativity of M is less than (Ve + 6.74) / 5.41.
[0023] In this general expression, the value of x is normally 1 < x<- 2.5, preferably 1.5 5 x s 2.5, and more preferably 1.75 s x s 2.5. If the value of x is equal to or less than 1, in theory Fe cannot take on a valence of 4. Conversely, if the value of x is too large, amorphous electrode active material cannot be obtained.
[0024] In the foregoing general expression, the value of y is normally 0 < y s 3, preferably 1.5 s y s 3, and more preferably 1.5 <_ y s 2.5. If the value of y is too small, amorphous electrode active material cannot be obtained. On the other hand, if the value of y is too large, the capacity becomes smaller such that practical electrode active material cannot be obtained.
[0025] In the foregoing general expression, the value of z changes depending on the value of x, the valence of Fe, the valence, of M, and the value of y, but it is normally represented by z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry. That is, in this example embodiment of the invention, the value of z is specified to satisfy electroneutrality. Incidentally, in the example embodiment of the invention, the valence of Fe changes from 2 to 4 with charging and discharging, but when the electrode active material according to this example embodiment of the invention is synthesized using a melt rapid cooling method, which will be described later, for example, the valence of Fe is usually 2 or 3.
[0026] In the foregoing general expression, M represents one or two or more types of glass former element. The M is not particularly limited as long as it is an element that forms glass. More specifically, the M may be, for example, boron (B), phosphorus (P), silicon (Si), or tin (Sn). Of these, boron (B) is preferable because the electronegativity is within the appropriate range which enables the capacity of the electrode active material to be high.
[0027] In' the foregoing general expression, the average electronegativity of M, is less than (Ve + 6.74) / 5.41. Incidentally, the electrolyte decomposition potential Ve will be described later in relation to the electrolyte solution that is used together with the electrode active material. The term electronegativity in this example embodiment of the invention, refers to Pauling electronegativity. More specifically, boron (B) is 2.04, phosphorus (P) is 2.19, silicon (Si) is 1.90, and tin (Sn) is 1.96. Also, the term average electronegativity in this example embodiment of the invention refers to the weighted average of the electronegativity of each element that constitutes or forms M.
For example, when M is formed of boron, (B) and phosphorus (P) such that M=
B1.sPo.5, the average electronegativity is ((2.04 x 1.5) + (2.19 x 0.5)) / (1.5 + 0.5) =
2.08.
For example, when M is formed of boron, (B) and phosphorus (P) such that M=
B1.sPo.5, the average electronegativity is ((2.04 x 1.5) + (2.19 x 0.5)) / (1.5 + 0.5) =
2.08.
[0028] Here, when the average electronegativity of M is equal to (Ve + 6.74) /
5.41, the oxidation potential from trivalent to quadrivalent Fe becomes equal to the decomposition potential of the electrolyte solution so the electrolyte solution ends up decomposing simultaneously with the oxidation of the Fe. Therefore, the average electronegativity of M simply needs to be less than (Ve + 6.74) / 5.41, preferably equal to or less than ((Ve + 6.74) / 5.41) - 0.05, and more preferably equal to or less than ((Ve +
6.74) / 5.41) - 0.1 because it enables the high electrode active material to be safer.
5.41, the oxidation potential from trivalent to quadrivalent Fe becomes equal to the decomposition potential of the electrolyte solution so the electrolyte solution ends up decomposing simultaneously with the oxidation of the Fe. Therefore, the average electronegativity of M simply needs to be less than (Ve + 6.74) / 5.41, preferably equal to or less than ((Ve + 6.74) / 5.41) - 0.05, and more preferably equal to or less than ((Ve +
6.74) / 5.41) - 0.1 because it enables the high electrode active material to be safer.
[0029] Although the range of the average electronegativity of M differs depending on the decomposition potential of the electrolyte solution and the like, it is preferably equal to or less than 2.17, and more preferably equal to or less than 2.07.
[0030] One characteristic of the electrode active material according to the example embodiment of the invention is that it is amorphous. This electrode active material is preferably amorphous to the extent that one or two or more of the following conditions are satisfied. (1) the average crystallite size is equal to or less than approximately 1000 Angstrom (preferably equal to or less than approximately Angstrom, and more preferably equal to or less than 50 Angstrom); (2) the specific gravity of the electrode active material is large at equal to or greater than approximately 3% (and more preferably equal to or greater than approximately 5%) compared to the specific gravity (theoretical value) when the electrode active material is completely crystalline; and (3) no peak which supports the electrode active material being crystalline can be observed in an X-ray diffraction pattern. The electrode active material described here is preferably electrode active material that satisfies one or two or more of these conditions (1) to (3). Of these, the electrode active material is preferably an electrode active materiaj that satisfies at least condition (3). Incidentally, the -N-ray pattern can be obtained using an X-ray diffractometer (model number: Rigaku RINT 2100 HLR/PC) or the like that may be obtained from Rigaku Corporation, for example. The application effect of this example embodiment of the invention tends to become even greater with electrode active material that is more amorphous (i.e., less crystalline), [0031] Next, electrolyte solution that is used together with the electrode active material will be described. The electrode active material according to the example embodiment of the invention is used together with electrolyte solution having an electrolyte decomposition potential Ve. Incidentally, the unit of the electrolyte decomposition potential Ve is (V vs Li-metal), but for the sake of convenience may simply be referred to as V.
[0032] The electrolyte decomposition potential Ve differs depending on the composition of the electrolyte solution used, and although not particularly limited, is preferably within the range of 4.00 V to 5.00 V, and more preferably within the range of 4.00 V to 4.50 V, for example. Incidentally, the highest decomposition potential of any practical electrolyte solution currently being used is approximately 4.50 V.
However, in this example embodiment of the invention, sufficient effects of the example embodiment of the invention are displayed even if an electrolyte solution having a decomposition potential that exceeds 4.50 V is used. The decomposition potential can be determined by the value listed in a chemical pamphlet or the like or by the measurement results when an actual decomposition experiment is performed on the electrolyte solution.
However, in this example embodiment of the invention, sufficient effects of the example embodiment of the invention are displayed even if an electrolyte solution having a decomposition potential that exceeds 4.50 V is used. The decomposition potential can be determined by the value listed in a chemical pamphlet or the like or by the measurement results when an actual decomposition experiment is performed on the electrolyte solution.
[0033] The electrolyte solution normally contains a supporting salt and a solvent. The supporting salt can be any of a variety of lithium salts such as LiPF6, LiBF4, LiN(CF3SO2)2, LiCF3SO3, LiC.ASO3, LiC(CF3SO2)3, and LiC1O4, for example.
The solvent may be any of a variety of types of aprotic solvents such as a carbonate, ester, ether, nitrile, sulfone, or lactone type, or ambient temperature molten salt, for example.
Specific examples include propylene carbonate; ethylene carbonate; diethyl carbonate;
dimethyl carbonate; ethyl methyl carbonate; 1, 2-dimethoxyethane; 1, 2-diethoxyethane;
acetonitrile; propionitrile; tetrahydrofuran; 2-methyltetrahydrofuran;
dioxane; 1, 3-dioxolan; nitrorpethane; N, N-dimethylformamide; dimethylsulfoxioe;
sulfolane;
y-butyrolactone, and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4).
In this example embodiment of the invention, only one type or a mixture of two or more types of these solvents may be used.
The solvent may be any of a variety of types of aprotic solvents such as a carbonate, ester, ether, nitrile, sulfone, or lactone type, or ambient temperature molten salt, for example.
Specific examples include propylene carbonate; ethylene carbonate; diethyl carbonate;
dimethyl carbonate; ethyl methyl carbonate; 1, 2-dimethoxyethane; 1, 2-diethoxyethane;
acetonitrile; propionitrile; tetrahydrofuran; 2-methyltetrahydrofuran;
dioxane; 1, 3-dioxolan; nitrorpethane; N, N-dimethylformamide; dimethylsulfoxioe;
sulfolane;
y-butyrolactone, and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4).
In this example embodiment of the invention, only one type or a mixture of two or more types of these solvents may be used.
[0034] Next, the manufacturing method of the electrode active material according to a second example embodiment of the invention will be described.
The manufacturing method of the electrode active material according to this example embodiment of the invention is not particularly limited as long as it is a method by which the electrode active material described above can be obtained. One example is the melt 5 rapid cooling method. One specific example of the melt rapid cooling method is a method for melt mixing a raw material composition that includes the raw materials which constitute the general expression LixFeMyOZ, and rapidly solidifying that raw material composition from a molten state. The raw material composition normally contains Li raw material, Fe raw material, and M raw material.
10 [0035] The Li raw material is not particularly limited as long as it contains a Li element. For example, the Li raw material may be Li20, LiOH, or Li2CO3 or the like.
Of these, Li20 is preferable. In this example embodiment of the invention, one or two or more types of the Li raw material may be used. The Fe raw material is not particularly limited as long as it contains an Fe element. For example, the Fe raw material may be FeO or Fe203, FeO being the more preferable. In this example embodiment of the invention, one or two or more types of the Fe raw material may be used.
[0036] The M raw material is not particularly limited as long as it includes the glass former element described above. Examples of the M raw material include hydroxide and oxide having the glass former element described above. More specifically, when the glass former element is boron (B), B203 or the like may be used.
When the glass former element is phosphorus (P), P205 or the like may be used.
When the glass former element is silicon (Si), Si02 or the like may be used. When the glass former element is tin (Sn), Sn02 or the like may be used. In this example embodiment of the invention, one Qr two or more types of the M may be used. In thi~
example embodiment of the invention, the type and amount of the M that is used are set so that the average electronegativity of M is less than the value described above.
[0037] In this example embodiment of the invention, amorphous electrode active material may be obtained by adjusting the composition of the raw material composition to match the target element ratio, melting that raw material composition at approximately 1200 C, for example, and then rapidly cooling it using a single-roll rapid cooling apparatus provided with a Cu roll.
[0038] Next, a lithium secondary battery according to a third example embodiment of the invention will be described. The lithium secondary battery according to the example embodiment of the invention includes a positive electrode layer that includes the foregoing electrode active material as positive electrode active material;
a negative electrode layer that includes negative electrode active material; a separator arranged between the positive electrode layer and the negative electrode layer; and an electrolyte solution having an electrolyte decomposition potential Ve which is impregnated into at least the separator.
[0039] According to this example embodiment of the invention, a high capacity lithium secondary battery can be obtained by combining the foregoing electrode active material with the foregoing electrolyte, solution. That is, as shown in described above, trivalent-quadrivalent redox of Fe can be used by setting the value of the average electronegativity of M in amorphous electrode active material represented by the general expression LiYFeMYOZ according to the electrolyte decomposition potential Ve.
The ability to utilize this trivalent-quadrivalent redox of Fe enables a high capacity lithium secondary battery to be obtained.
[0040] The electrode active material and the electrolyte solution used in this example embodiment of the invention are the same as the electrode active material and the electrolyte sol'ution in the first example embodiment of the invention so descriptions thereof will be omitted here. Also, the structure of the lithium secondary battery according to this example embodiment of the invention is not particularly limited and may be set as deemed apprppriate as long as it at least has the foregoing elec.trode active material and the foregoing electrolyte solution.
[0041] The positive electrode layer normally includes a conductive agent and a binder in addition to the positive electrode active material. The conductive agent may be, for example, carbon black or acetylene black. The binder may be, for example, polyvinylidene-fluoride (PVDF) or polytetrafluoroethylene (PTFE). Also, the lithium secondary battery according to this example embodiment of the invention may also have a positive electrode collector that collects power from the positive electrode layer. The material of this positive electrode collector may be, for example, stainless steel, nickel, aluminum, iron, or titanium.
[0042] The negative electrode layer normally includes negative electrode active material, a conductive agent, and a binder. The negative electrode active material is not particularly limited as long as it can store and release lithium ions.
Examples include metal lithium, a lithium alloy, metal oxide, metal sulfide, metal nitride, and carbon material such as graphite. Of these, metal lithium is preferable. The conductive agent and the binder can be the same as those used with the positive electrode layer described above. Also, the lithium secondary battery according to this example embodiment of the invention may have a negative electrode collector that collects power from the negative electrode layer. The material of the negative electrode collector may be, for example, copper, stainless steel or nickel.
[0043] The separator is not particularly limited as long as it functions to separate the positive electrode layer from the negative electrode layer and hold the electrolyte solution. Possible examples include a porous membrane such as polyethylene or polypropylene, and nonwoven fabric such as resin nonwoven fabric or glass fiber nonwoven fabric. Also, the lithium secondary battery obtained from the example embodiment of the invention may be any of a variety of shapes, such as coin-shaped, laminated (stacked), or cylindrical.
[0044] Incidentally, the. invention is not limited to the foregoing example embodiments. The foregoing example embodiments illustrate examples. Other examples having substantially the, same structure as the technical ideas described within the scope of the claims for patent of the invention and displaying the same operation and effects are also included within the technical scope of the invention.
[0045] Hereinafter, the invention will be described in even more detail with the following examples. LiOH as the Li raw material, FeO as the Fe raw material, P205 as.
the P raw material, and B203 as the B raw material were prepared. Using these raw materials, raw material components A to C were then obtained by mixing the constituent components together so that the molar ratio was the same as that shown in Chart 1 below.
[0046]
[Chart 1]
Li:Fe:P:B
Raw material composition A 2: 1: 1.5 : 0 Raw material composition B 2: 1: 1: 1 Raw material composition C 2: 1: 0: 2 [0047] Next, the raw material components were melted for 1 minute at 1200 C
in an Ar atmosphere and then rapidly cooled with a single-roll rapid cooling apparatus provided with a Cu roll to obtain electrode active materials A to C. The crystallinity of each of the obtained electrode active materials A to C was then evaluated using X-ray diffraction under the following measurement conditions: Apparatus used:
Rigaku, RAD-X; X-ray: CuKa, 40 kV, 40 mA; scan range: 2 6= 10 to 80 . In the results, no peak which supports crystallinity could be observed in an X-ray diffraction pattern for any of the electrode active materials A to C so the electrode active materials A to C were all confirmed to be amorphous.
[0048] Next, test cells were manufactured using the electrode active materials A to C and the charging and discharging characteristics of each cell were evaluated.
First, 0.4 grams of electrode active material A was weighed out and added to a zirconia mill pot. Ball mill processing was then performed for 3 hours at 300 rpm.
Next, 0.1429 grams of acetylene black was added and ball mill processing was performed for, another 3 hours at 300 rpm. Then 0.053 grams of PTFE was added to the obtained powder and this mixture was then applied to SUS mesh to obtain a positive electrode.
[0049] Next, metal lithium as the counter electrode and a polyethylene separator (Ube Industries, Ltd.) were prepared. Also, the electrolyte solution was prepared by dissolving 1 moi/L of LiPF6 as a supporting salt in a mixed solvent having a volume ratio of 3 : 7 of ethylene carbonate (EC) and diethyl carbonate (DEC).
Test cell A which is a 2032 type coin cell was obtained using these materials. Then test cells B
and C were obtained in the same way except for that electrode active materials B and C, respectively, were used instead of electrode active material A.
[0050] Next, charging and discharging using the test cells A to C obtained as described above were performed under the following conditions: Charging: 4.5 V, CC157 VA, Rest: 5 min, Discharging: 1.5 V, CC157 ErA, Rest: 5 min.
[0051] FIG. 2 is a graph in which the obtained charging and discharging curves have been converted into differential capacity. As is evident from FIG 2, divalent-trivalent redox of Fe was confirmed in test cells A and B, though trivalent-quadrivalent redox of Fe was not. On the other hand, in test cell C, an oxidation potential of trivalent-quadrivalent Fe near 4.3 V, as well as an oxidation potential of divalent-trivalent Fe near 2.5 V was observed.
[0052] A compilation of the results of FIG. 2 are shown in Chart 2 below.
[0053]
[Chart 2]
Electrode active Average Oxidation Oxidation material electronegativity potential (V) of potential (V) of composition of M Fe Fe (divalent -~ (trivalent trivalent quadrivalent Test cell A LUeP1.5OZ 2.19 3.30 Not observed Test cell B Li2FeP1BlOZ 2.1? 2.96 Not observed Test cell C Li2Fe&2OZ 2.04 2.49 4.29 * In the expressions, z is a number that satisfies electroneutrality.
[0054] FIG. 3 is a graph in which the x-axis represents the average electronegativity of M and the y-axis represents the oxidation potential. As is evident from FIG. 3, it was confirmed that when the average electronegativity of M
decreases, the oxidation potential from divalent to trivalent Fe also decreases.
Incidentally, in FIG. 3, the straight line of the oxidation potential from divalent to trivalent Fe and the straight line of the oxidation potential from trivalent to quadrivalent Fe are parallel. This is because the redox potential is determined by the relationship between an inherent potential that an Fe valence= change has and an electronegativity that an element (Li, M, 0) around the Fe has. Furthermore, taking into consideration that the decomposition voltage of the electrolyte solution used in this example is 4.50 V, the average electronegativity of M must be equal to or less than 2.07 to realize trivalent-quadrivalent 5 redox of Fe. The average electronegativity of M in both test cells A and B
is higher than approximately 2.07 , so in actuality test cells A and B were unable to utilize trivalent-quadrivalent redox. The average electronegativity of M in test cell C, however, is lower than approximately 2.07 so test cell C was able to utilize trivalent-quadrivalent redox.
The manufacturing method of the electrode active material according to this example embodiment of the invention is not particularly limited as long as it is a method by which the electrode active material described above can be obtained. One example is the melt 5 rapid cooling method. One specific example of the melt rapid cooling method is a method for melt mixing a raw material composition that includes the raw materials which constitute the general expression LixFeMyOZ, and rapidly solidifying that raw material composition from a molten state. The raw material composition normally contains Li raw material, Fe raw material, and M raw material.
10 [0035] The Li raw material is not particularly limited as long as it contains a Li element. For example, the Li raw material may be Li20, LiOH, or Li2CO3 or the like.
Of these, Li20 is preferable. In this example embodiment of the invention, one or two or more types of the Li raw material may be used. The Fe raw material is not particularly limited as long as it contains an Fe element. For example, the Fe raw material may be FeO or Fe203, FeO being the more preferable. In this example embodiment of the invention, one or two or more types of the Fe raw material may be used.
[0036] The M raw material is not particularly limited as long as it includes the glass former element described above. Examples of the M raw material include hydroxide and oxide having the glass former element described above. More specifically, when the glass former element is boron (B), B203 or the like may be used.
When the glass former element is phosphorus (P), P205 or the like may be used.
When the glass former element is silicon (Si), Si02 or the like may be used. When the glass former element is tin (Sn), Sn02 or the like may be used. In this example embodiment of the invention, one Qr two or more types of the M may be used. In thi~
example embodiment of the invention, the type and amount of the M that is used are set so that the average electronegativity of M is less than the value described above.
[0037] In this example embodiment of the invention, amorphous electrode active material may be obtained by adjusting the composition of the raw material composition to match the target element ratio, melting that raw material composition at approximately 1200 C, for example, and then rapidly cooling it using a single-roll rapid cooling apparatus provided with a Cu roll.
[0038] Next, a lithium secondary battery according to a third example embodiment of the invention will be described. The lithium secondary battery according to the example embodiment of the invention includes a positive electrode layer that includes the foregoing electrode active material as positive electrode active material;
a negative electrode layer that includes negative electrode active material; a separator arranged between the positive electrode layer and the negative electrode layer; and an electrolyte solution having an electrolyte decomposition potential Ve which is impregnated into at least the separator.
[0039] According to this example embodiment of the invention, a high capacity lithium secondary battery can be obtained by combining the foregoing electrode active material with the foregoing electrolyte, solution. That is, as shown in described above, trivalent-quadrivalent redox of Fe can be used by setting the value of the average electronegativity of M in amorphous electrode active material represented by the general expression LiYFeMYOZ according to the electrolyte decomposition potential Ve.
The ability to utilize this trivalent-quadrivalent redox of Fe enables a high capacity lithium secondary battery to be obtained.
[0040] The electrode active material and the electrolyte solution used in this example embodiment of the invention are the same as the electrode active material and the electrolyte sol'ution in the first example embodiment of the invention so descriptions thereof will be omitted here. Also, the structure of the lithium secondary battery according to this example embodiment of the invention is not particularly limited and may be set as deemed apprppriate as long as it at least has the foregoing elec.trode active material and the foregoing electrolyte solution.
[0041] The positive electrode layer normally includes a conductive agent and a binder in addition to the positive electrode active material. The conductive agent may be, for example, carbon black or acetylene black. The binder may be, for example, polyvinylidene-fluoride (PVDF) or polytetrafluoroethylene (PTFE). Also, the lithium secondary battery according to this example embodiment of the invention may also have a positive electrode collector that collects power from the positive electrode layer. The material of this positive electrode collector may be, for example, stainless steel, nickel, aluminum, iron, or titanium.
[0042] The negative electrode layer normally includes negative electrode active material, a conductive agent, and a binder. The negative electrode active material is not particularly limited as long as it can store and release lithium ions.
Examples include metal lithium, a lithium alloy, metal oxide, metal sulfide, metal nitride, and carbon material such as graphite. Of these, metal lithium is preferable. The conductive agent and the binder can be the same as those used with the positive electrode layer described above. Also, the lithium secondary battery according to this example embodiment of the invention may have a negative electrode collector that collects power from the negative electrode layer. The material of the negative electrode collector may be, for example, copper, stainless steel or nickel.
[0043] The separator is not particularly limited as long as it functions to separate the positive electrode layer from the negative electrode layer and hold the electrolyte solution. Possible examples include a porous membrane such as polyethylene or polypropylene, and nonwoven fabric such as resin nonwoven fabric or glass fiber nonwoven fabric. Also, the lithium secondary battery obtained from the example embodiment of the invention may be any of a variety of shapes, such as coin-shaped, laminated (stacked), or cylindrical.
[0044] Incidentally, the. invention is not limited to the foregoing example embodiments. The foregoing example embodiments illustrate examples. Other examples having substantially the, same structure as the technical ideas described within the scope of the claims for patent of the invention and displaying the same operation and effects are also included within the technical scope of the invention.
[0045] Hereinafter, the invention will be described in even more detail with the following examples. LiOH as the Li raw material, FeO as the Fe raw material, P205 as.
the P raw material, and B203 as the B raw material were prepared. Using these raw materials, raw material components A to C were then obtained by mixing the constituent components together so that the molar ratio was the same as that shown in Chart 1 below.
[0046]
[Chart 1]
Li:Fe:P:B
Raw material composition A 2: 1: 1.5 : 0 Raw material composition B 2: 1: 1: 1 Raw material composition C 2: 1: 0: 2 [0047] Next, the raw material components were melted for 1 minute at 1200 C
in an Ar atmosphere and then rapidly cooled with a single-roll rapid cooling apparatus provided with a Cu roll to obtain electrode active materials A to C. The crystallinity of each of the obtained electrode active materials A to C was then evaluated using X-ray diffraction under the following measurement conditions: Apparatus used:
Rigaku, RAD-X; X-ray: CuKa, 40 kV, 40 mA; scan range: 2 6= 10 to 80 . In the results, no peak which supports crystallinity could be observed in an X-ray diffraction pattern for any of the electrode active materials A to C so the electrode active materials A to C were all confirmed to be amorphous.
[0048] Next, test cells were manufactured using the electrode active materials A to C and the charging and discharging characteristics of each cell were evaluated.
First, 0.4 grams of electrode active material A was weighed out and added to a zirconia mill pot. Ball mill processing was then performed for 3 hours at 300 rpm.
Next, 0.1429 grams of acetylene black was added and ball mill processing was performed for, another 3 hours at 300 rpm. Then 0.053 grams of PTFE was added to the obtained powder and this mixture was then applied to SUS mesh to obtain a positive electrode.
[0049] Next, metal lithium as the counter electrode and a polyethylene separator (Ube Industries, Ltd.) were prepared. Also, the electrolyte solution was prepared by dissolving 1 moi/L of LiPF6 as a supporting salt in a mixed solvent having a volume ratio of 3 : 7 of ethylene carbonate (EC) and diethyl carbonate (DEC).
Test cell A which is a 2032 type coin cell was obtained using these materials. Then test cells B
and C were obtained in the same way except for that electrode active materials B and C, respectively, were used instead of electrode active material A.
[0050] Next, charging and discharging using the test cells A to C obtained as described above were performed under the following conditions: Charging: 4.5 V, CC157 VA, Rest: 5 min, Discharging: 1.5 V, CC157 ErA, Rest: 5 min.
[0051] FIG. 2 is a graph in which the obtained charging and discharging curves have been converted into differential capacity. As is evident from FIG 2, divalent-trivalent redox of Fe was confirmed in test cells A and B, though trivalent-quadrivalent redox of Fe was not. On the other hand, in test cell C, an oxidation potential of trivalent-quadrivalent Fe near 4.3 V, as well as an oxidation potential of divalent-trivalent Fe near 2.5 V was observed.
[0052] A compilation of the results of FIG. 2 are shown in Chart 2 below.
[0053]
[Chart 2]
Electrode active Average Oxidation Oxidation material electronegativity potential (V) of potential (V) of composition of M Fe Fe (divalent -~ (trivalent trivalent quadrivalent Test cell A LUeP1.5OZ 2.19 3.30 Not observed Test cell B Li2FeP1BlOZ 2.1? 2.96 Not observed Test cell C Li2Fe&2OZ 2.04 2.49 4.29 * In the expressions, z is a number that satisfies electroneutrality.
[0054] FIG. 3 is a graph in which the x-axis represents the average electronegativity of M and the y-axis represents the oxidation potential. As is evident from FIG. 3, it was confirmed that when the average electronegativity of M
decreases, the oxidation potential from divalent to trivalent Fe also decreases.
Incidentally, in FIG. 3, the straight line of the oxidation potential from divalent to trivalent Fe and the straight line of the oxidation potential from trivalent to quadrivalent Fe are parallel. This is because the redox potential is determined by the relationship between an inherent potential that an Fe valence= change has and an electronegativity that an element (Li, M, 0) around the Fe has. Furthermore, taking into consideration that the decomposition voltage of the electrolyte solution used in this example is 4.50 V, the average electronegativity of M must be equal to or less than 2.07 to realize trivalent-quadrivalent 5 redox of Fe. The average electronegativity of M in both test cells A and B
is higher than approximately 2.07 , so in actuality test cells A and B were unable to utilize trivalent-quadrivalent redox. The average electronegativity of M in test cell C, however, is lower than approximately 2.07 so test cell C was able to utilize trivalent-quadrivalent redox.
Claims (5)
1. Electrode active material provided with an electrolyte solution having an electrolyte decomposition potential Ve, wherein the electrode active material is amorphous; and the electrode active material is represented by a general expression Li x FeM y O z, wherein in the expression, x and y are values which independently satisfy 1 < x <= 2.5 and 0 < y <= 3, respectively, and z = (x +
(valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M
represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve +
6.74) / 5.41.
(valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M
represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve +
6.74) / 5.41.
2. The electrode active material according to claim 1, wherein the average electronegativity of M is equal to or less than 2.07.
3. The electrode active material according to claim 1 or 2, wherein the M is boron.
4. A manufacturing method of electrode active material provided with an electrolyte solution having an electrolyte decomposition potential Ve, comprising:
melt mixing raw material composition that includes raw materials that constitute a general expression Li x FeM y O z; and rapidly solidifying from a molten state the raw material composition that was melt mixed, wherein in the expression, x and y are values which independently satisfy 1 <
x <= 2.5 and 0 < y <= 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve + 6.74) / 5.41.
melt mixing raw material composition that includes raw materials that constitute a general expression Li x FeM y O z; and rapidly solidifying from a molten state the raw material composition that was melt mixed, wherein in the expression, x and y are values which independently satisfy 1 <
x <= 2.5 and 0 < y <= 3, respectively, and z = (x + (valence of Fe) + (valence of M) x y) / 2 to satisfy stoichiometry, M represents one or two or more types of glass former element, and an average electronegativity of M is less than (Ve + 6.74) / 5.41.
5. A lithium secondary battery comprising:
a positive electrode layer that includes the electrode active material according to any one of claims 1 to 3 as positive electrode active material;
a negative electrode layer that includes negative electrode active material;
a separator arranged between the positive electrode layer and the negative electrode layer;
and an electrolyte solution having an electrolyte decomposition potential Ve which is impregnated into at least the separator.
a positive electrode layer that includes the electrode active material according to any one of claims 1 to 3 as positive electrode active material;
a negative electrode layer that includes negative electrode active material;
a separator arranged between the positive electrode layer and the negative electrode layer;
and an electrolyte solution having an electrolyte decomposition potential Ve which is impregnated into at least the separator.
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| JP2007094502A JP5164246B2 (en) | 2007-03-30 | 2007-03-30 | Electrode active material and lithium secondary battery |
| JP2007-094502 | 2007-03-30 | ||
| PCT/IB2008/001553 WO2008120106A2 (en) | 2007-03-30 | 2008-03-28 | Electrode active materialand lithium secondary battery |
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| US (1) | US8703334B2 (en) |
| EP (1) | EP2137778B1 (en) |
| JP (1) | JP5164246B2 (en) |
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| AT (1) | ATE523917T1 (en) |
| BR (1) | BRPI0809584A2 (en) |
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| JP5489627B2 (en) * | 2009-10-02 | 2014-05-14 | トヨタ自動車株式会社 | Lithium secondary battery |
| JP5506358B2 (en) * | 2009-12-11 | 2014-05-28 | パナソニック株式会社 | Non-aqueous electrolyte battery active material and non-aqueous electrolyte battery |
| JP6837278B2 (en) * | 2015-02-25 | 2021-03-03 | 国立大学法人長岡技術科学大学 | Positive electrode active material for alkaline ion secondary batteries |
| WO2016136555A1 (en) * | 2015-02-25 | 2016-09-01 | 国立大学法人長岡技術科学大学 | Positive electrode active material for alkali ion secondary batteries |
| CN115832288A (en) | 2015-10-28 | 2023-03-21 | 日本电气硝子株式会社 | Positive electrode active material for sodium ion secondary battery |
| CN110521036A (en) * | 2017-06-27 | 2019-11-29 | 日本电气硝子株式会社 | Sodium ion secondary battery positive active material |
| JP6662353B2 (en) * | 2017-07-18 | 2020-03-11 | トヨタ自動車株式会社 | Negative electrode current collector, negative electrode, and aqueous lithium ion secondary battery |
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| GB744947A (en) | 1953-09-14 | 1956-02-15 | British Thomson Houston Co Ltd | Improvements in glass compositions |
| JP3393621B2 (en) | 1993-06-07 | 2003-04-07 | 本田技研工業株式会社 | Positive electrode material for lithium secondary battery and method for producing the same |
| JPH0878002A (en) | 1994-08-31 | 1996-03-22 | Yamaha Corp | Lithium battery and manufacture of its electrode |
| JPH0922695A (en) | 1995-07-04 | 1997-01-21 | Mitsubishi Cable Ind Ltd | Electrode for lithium secondary battery and lithium secondary battery using same |
| JP3593808B2 (en) | 1996-09-02 | 2004-11-24 | ヤマハ株式会社 | Method for manufacturing electrode of lithium battery |
| JP3424722B2 (en) | 1996-10-29 | 2003-07-07 | 日本電信電話株式会社 | Positive active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery |
| CA2320661A1 (en) * | 2000-09-26 | 2002-03-26 | Hydro-Quebec | New process for synthesizing limpo4 materials with olivine structure |
| JP2002270171A (en) | 2001-03-08 | 2002-09-20 | Nissan Motor Co Ltd | Positive electrode active material for non-aqueous electrolyte lithium secondary battery and producing method thereof |
| CN1205689C (en) | 2001-09-28 | 2005-06-08 | 任晓平 | Secondary lithium ion battery or battery pack, its protective circuit and electronic device |
| JP4543658B2 (en) | 2003-10-31 | 2010-09-15 | トヨタ自動車株式会社 | Electrode active material, method for producing the same, and nonaqueous electrolyte secondary battery |
| JP2005158673A (en) * | 2003-10-31 | 2005-06-16 | Toyota Motor Corp | Electrode active material, manufacturing method therefor and non-aqueous secondary battery |
| CA2791156C (en) * | 2003-12-23 | 2015-12-15 | Universite De Montreal | Process for preparing electroactive insertion compounds and electrode materials obtained therefrom |
| US7648801B2 (en) | 2004-04-01 | 2010-01-19 | 3M Innovative Properties Company | Redox shuttle for overdischarge protection in rechargeable lithium-ion batteries |
| JP2006155941A (en) * | 2004-11-25 | 2006-06-15 | Kyushu Univ | Method of manufacture for electrode active material |
| JP2007234565A (en) * | 2005-03-18 | 2007-09-13 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
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| EP2137778A2 (en) | 2009-12-30 |
| ATE523917T1 (en) | 2011-09-15 |
| CN101657919B (en) | 2012-07-04 |
| KR101145997B1 (en) | 2012-05-15 |
| WO2008120106A3 (en) | 2009-10-22 |
| JP2008251481A (en) | 2008-10-16 |
| KR20090121366A (en) | 2009-11-25 |
| US20100183923A1 (en) | 2010-07-22 |
| RU2009135868A (en) | 2011-05-10 |
| US8703334B2 (en) | 2014-04-22 |
| JP5164246B2 (en) | 2013-03-21 |
| RU2433509C2 (en) | 2011-11-10 |
| EP2137778B1 (en) | 2011-09-07 |
| CA2682094C (en) | 2013-07-23 |
| CN101657919A (en) | 2010-02-24 |
| WO2008120106A8 (en) | 2009-01-08 |
| BRPI0809584A2 (en) | 2014-09-23 |
| WO2008120106A2 (en) | 2008-10-09 |
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